Btrfs: prepare block group cache before writing

Writing the block group cache will modify the extent tree quite a bit because it
truncates the old space cache and pre-allocates new stuff.  To try and cut down
on the churn lets do the setup dance first, then later on hopefully we can avoid
looping with newly dirtied roots.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fb.com>
(cherry picked from commit aa4661f6a7aee90423d1c77ee4d492e7b1a99883)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 47fba0af81c199bc2c078a55af6d4c6d9e79f2db..07192e0a18943cb8b4a6a241bba20a10c3b4f568 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3320,6 +3320,8 @@ int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
 
 int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
                                    struct btrfs_root *root);
+int btrfs_setup_space_cache(struct btrfs_trans_handle *trans,
+                           struct btrfs_root *root);
 int btrfs_extent_readonly(struct btrfs_root *root, u64 bytenr);
 int btrfs_free_block_groups(struct btrfs_fs_info *info);
 int btrfs_read_block_groups(struct btrfs_root *root);

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index cf90e22098efc0b86b80afc256e74b001655ae12..b67987a33537ee2759bf5cbb2165f595dac90865 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3311,6 +3311,32 @@ out:
        return ret;
 }
 
+int btrfs_setup_space_cache(struct btrfs_trans_handle *trans,
+                           struct btrfs_root *root)
+{
+       struct btrfs_block_group_cache *cache, *tmp;
+       struct btrfs_transaction *cur_trans = trans->transaction;
+       struct btrfs_path *path;
+
+       if (list_empty(&cur_trans->dirty_bgs) ||
+           !btrfs_test_opt(root, SPACE_CACHE))
+               return 0;
+
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+
+       /* Could add new block groups, use _safe just in case */
+       list_for_each_entry_safe(cache, tmp, &cur_trans->dirty_bgs,
+                                dirty_list) {
+               if (cache->disk_cache_state == BTRFS_DC_CLEAR)
+                       cache_save_setup(cache, trans, path);
+       }
+
+       btrfs_free_path(path);
+       return 0;
+}
+
 int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
                                   struct btrfs_root *root)
 {

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 36d0d80cd2b94843df1476d5d53f040402882856..b7be7a6ad3b1f80337bf7a87726b345096038016 100644 (file)
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -960,7 +960,6 @@ static int update_cowonly_root(struct btrfs_trans_handle *trans,
        struct btrfs_root *tree_root = root->fs_info->tree_root;
 
        old_root_used = btrfs_root_used(&root->root_item);
-       btrfs_write_dirty_block_groups(trans, root);
 
        while (1) {
                old_root_bytenr = btrfs_root_bytenr(&root->root_item);
@@ -1024,6 +1023,10 @@ static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
        if (ret)
                return ret;
 
+       ret = btrfs_setup_space_cache(trans, root);
+       if (ret)
+               return ret;
+
        /* run_qgroups might have added some more refs */
        ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
        if (ret)